Integration of wireless local area networks (WLANs) with other wireless access technologies has become increasingly important among the various standards that develop wireless access technologies. Handover mechanisms and procedures that might allow seamless delivery of services across heterogeneous networks are of prime importance towards multi-technology integration.
In particular within IEEE standards, 802.21 has been tasked with providing mechanisms and notification that enable other technologies to react quickly to changing conditions within the WLAN network itself. These notifications provide details with regard to the current state of the WLAN or access technology supplying a service.
Link quality, (e.g., received signal strength indicator (RSSI), bit error rate (BER), packet error rate (PER)), link capabilities to support a particular service, (e.g., voice or high speed data), and details on the service provider that delivers the service are examples of the information that 802.21 can provide. This information allows existing mobility management mechanisms to set up alternate access resources in order to continue the delivery of services with the same or similar level of quality as originally requested by the user.
It is important to note that it is up to an access technology to determine the course of action to follow, at the upper layer, upon receipt of the notification and triggers. However, in order to avoid the so-called “ping-pong” effect, notifications hinting the need for a handover need to provide a validity period and action time that will allow the upper layer function to determine when the handover needs to occur.
In general handovers are triggered using two main criteria. Either the current link is no longer suitable or a better candidate has been found. Handover across heterogeneous networks entails determining the best candidate across all available access technologies within a region.
There are current proposals addressing selection and discovery of handover candidates that base their criteria on measurements and information centrally stored in the access point. Information is stored in the form of neighboring maps that provide a snap shot of the network and associate this information to different zones. This poses a problem as measurements are taken from the access point's perspective and not from the client station's perspective. This is particularly problematic when the base station or access points are moved frequently, as maps are not updated that frequently.
Although measurements and settings are kept centrally at the access point, the handover decision might be made at the client station (STA). However, said current proposals do not take into consideration measurements taken at the STA, even thought the STA itself is in the best position to measure on prospective candidates for handover.
Therefore, it would be desirable to provide a method and system for station location based neighbor determination and handover probability without the limitations of the prior art.